Jet engines, chiefly turbo-jet engines provided with an auxiliary heating system



Feb. 18, 19".:'58 J J L BLANC '-2,823517.

JET ENGINES, CHIEF'LY'IURBo-JET ENGINES PROVIDED WITH AN AUXILIARY HEATING SYSTEM Filed NQv. 10, 1953 y United States Patent C) JET ENGINES, CHIEFLY TURBO-JET ENGINES WITH AN AUXILIARY HEATING Jacques Jean Louis Blanc, Paris, France, assignor to Societe dExplotation des Materiels Hispano-Suiza S. A., Bois-Colombes, France Application November 10, 1953, Serial No. 391,306

Claims priority, application France November 15, 1952 1 Claim. (Cl. 60-35.6)

The present invention relates to jet propulsion engines including an air compressor and in particular turbo-jet engines. The object of my invention is to provide an exhaust reheater system for an engine of this kind.

The exhaust reheater system includes a variable output fuel pump the delivery of which is connected with a fuel burner through a conduit including a linear flow valve mechanism, i. e. a valve mechanism across which the pressure drop is proportional to the flow of liquid through the valve, a pressure sensitive device being connected with said mechanism so as to be sensitive to the pressure drop across said valve mechanism, this pressure sensitive device being mounted to cooperate With another pressure sensitive device responsive to variations of the delivery pressure of said compressor so that the combined actions of said two -devices control the fuel pump to maintain the ow rate therefrom proportional to said compressor delivery pressure, said linear flow valve mechanism including a body having formed therein a seat around an orifice for the ow of fuel, the effective area of said seat being controlled by the head of a valve element loaded by a spring.

According to my invention, said spring is constituted by a flexible rod one end of which is rigidly fixed to said body and the other end of which carries said valve element, an abutment movably carried by said body along said rod and adjustable through suitable means determining the freely deformable portion lof said rod and therefore the action thereof on said valve element.

The invention will be readily understood from the reading of the following disclosure, reference being made to the accompanying drawings, said disclosure and drawings being given chiefly by Way of an exemplication. In said drawings:

Fig. 1 diagrammatically shows an exhaust reheater fuel feed system for a turbo-jet engine, said system being designed in accordance with the invention.

Fig. 2 Shows, on a larger scale, a by-pass incorporated in the exhaust reheater fuel feed system.

It will be supposed that the turbo-jet engine includes as illustrated, a propulsion nozzle 1 provided at its rear end with means for adjusting the cross-sectional area afforded for the outlet of the gases, said adjusting means including e. g. flaps 2 adapted to occupy two positions of which one corresponds to the maximum output crosssection, when the exhaust reheater system is operative, While the other position corresponds to the minimum output cross-section when the exhaust reheater system is inoperative.

The exhaust reheater includes at least one distributing fuel injection pipe or burner 3 preferably mounted across the flow of gases inside the nozzle 1, said pipe being fed with fuel by the pump 4.

This system is associated with means for adjusting automatically, as a function of the delivery pressure P2 of the engine air compressor, the flow of fuel D fed by the pump 4 tothe burner 3.

It will be assumed, hereinafter, by way of example that the pump 4 feeding fuel to burner 3 is a turbine driven pump including in the conventional manner a turbine section driven by a gas under pressure, such as air at the pressure P2 and a pump section, which may be of the centrifugal type.

Fig. 1 shows in interrupted lines the air circuit passing through the turbine section and in `solid lines the fuel circuit passing through the pump section.

There is inserted, in the circuit of the air feeding the turbine section, throttling means illustrated as a needle valve 5. A diaphragm 6a, separating the inside of the casing 6 into two chambers one of which, on the right hand side is at pressure P2, whereas a vacuum is maintained in the left hand side chamber, controls needle valve 5 through the agency of an auxiliary motor or valve-shift ing means 7, so that a variation in the value of P2 causes a variation in the same direction of the cross-sectional area for the air controlled by the needle valve 5 and consequently also of the flow of fuel delivered by the pump section of the turbine driven pump.

In the conduit (shown in solid lines on the drawing) connecting the discharge of pump 4 with burner 3, there is inserted a linear flow valve mechanism (i. e. a valve mechanism across which the pressure drop is proportional to the flow of liquid through the valve). This mechanism includes a body or casing 8 pr-ovided with a partition having formed therein a seat around an orifice for the passage of the fuel, a valve element 9 loaded by a spring 10 controlling the effective area of said orifice. The portions of casing 8 located on opposed sides of the partition in casing 8, that is to say respectively upstream.

and downstream of valve element 9, are connected to respective chambers 11 and 12 separated from each other by a diaphragm 13.

Diaphragms 6a and 13 are interconnected by a rod 14.

The rod 14 controls the movable part of the auxiliary motor 7. It is apparent that said movable part of the auxiliary motor is submitted to two stresses loperating in opposite directions, to Wit: a force developed by the diaphragm 6a and proportional to the pressure P2 (this force being therefore equal to K2P2, K2 being a constant coecient) and a force exerted by the diaphragm 13 and proportional to the actual ow D of fuel (this force being therefore equal to KlD, K1 eing a constant coefficient).

Under such conditions, and supposing the movable part of the auxiliary motor 7 is in a neutral inoperative position, said auxiliary motor will remain inoperative only if the following equation is satisfied:

Coecients K1 and K2 are determined by the different characteristics of the manometric capsule 6 and the valve mechanism 8, such as the surfaces of the diaphragms, the power of the valve spring lil, the cross-sectional area of the passage controlled by the valve 9, and if:

Kf'K

we have D=KP2, K being a fixed coefficient as long as the above-mentioned'characteristics remain unchanged.

Such an arrangement regulates the flow of fuel to the burner as a linear function of the pressure P2.

It is necessary to provide means for adjusting the strength of the spring 10 in ra manner as accurate and reliable as possible. For this purpose, in accordance with my invention, this spring is constituted by a flexible rod which cooperated with an abutment 15 adapted to be shifted along the length -of the said spring 10 by means of a controlling member 16, the flexibility of said spring varying consequently with the position of the abutment 15 along the said spring.

It is, as a rule, unnecessary to complete the regulating Patented Feb. 18, 1958- means by a further control of the fuel flow in accordance with the nozzle temperature T-4. However, if it is desired to obtain in all cases a still more accurate adjust ment, it is possible to resort to a further regulation through said temperature T-4. To this end, it is possible to provide an electric diierential device 17 which compares the actual temperature T-Ll detected by the thermocouple 1S and the preset temperature kas set at 19; said differential device 17 is caused to cooperate with driving means 20 controlling the movable part by a by-pass system 2l. This system is designed in a manner such that when the actual temperature is less than the preset temperature further amounts of fuel are introduced into the circuit while, in the opposite case, fuel is by-passed.

Fig. 2 illustrates diagrammatically said by-pass system including chiefly a slide-valve distributor which provides, when it has been shifted away from its neutral inoperative position, a communication of the pipe 22, inserted in the fuel circuit after the ilowmeter 8, selectively with a fuelintroducing pipe 23 tapped orf said circuit in the section comprised between the turbine driven pump 4 and the owmeter 8, or else, with a fuel-removing pipe 24'returning the excess fuel into the circuit before the said turbine driven pump.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and ecient embodiments of my invention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claim.

What I claim is:

For use in connection with a jet propulsion engine including an air compressor, an exhaust reheater system which comprises, in combination, a fuel burner, a variable `output fuelpump, a conduit connecting the delivery of said pump with said burner, a valve seat in said conduit limiting an orice for the ow of fuel therethrough, a valve member partly engaged inv said orice and slidable transversely to the plane of said seat, said valve member being shaped to vary the effective area of flow through said orice in accordance with the position of said valve member with respect to said seat, a resilient rod carrying, at one ot its ends said valve member to urge it toward said seat, the other end of said resilient rod being tightly held with respect to said conduit, an abutment slidable with respect to said conduit in a direction parallel to the general direction of said rod, means for adjusting the position of said abutment so as to determine the length of the freely deformable portion of said rod that is urging said valve member toward said valve seat, pressure responsive means differentially operative by the pressures existing in said conduit respectively upstream and downstream of said valve seat, pressure responsive mean operative by the delivery pressure of said compressor, and means operatively connected with both of said pressure responsive :means for controlling the output of said fuel pump to keep the ow rate of fuel delivered therefrom proportional to said compressor delivery pressure.

References Cited in the le of this patent UNITED STATES PATENTS 2,640,316 Neal June 2, 1953 2,653,446 Price Sept. 29, i953 2,668,415 Laurence Feb. 9, 1954 2,670,599 Davies et al. Mar. 2, 1954 2,714,803 Abild Aug. 9, 1955 

